1. Field of the Invention
This invention pertains to cooling systems for internal combustion engines, and more particularly for self-adjusting cooling systems for supercharged diesel engines.
2. Information Disclosure Statement
Heretofore, numerous attempts have been made to design cooling systems including means to cause a large recirculating flow through the jacket of the engine. These systems used dual coolant circuits. The U.S. Pat. Nos. 4,348,991; 3,134,371; and 2,841,127 exemplify the existing cooling systems of this kind.
The efficiency of an internal combustion engine can be improved by carefully controlling the operating temperature of the engine and the air charge supplied thereto. The temperature control is also important to the abatement of certain types of undesired emissions. However, the ideal temperature of achieving maximum efficiency as well as emission abatement is not the same for all operating conditions of the engine nor is it the same for all engine components and air charge. If the engine is turbocharged, then an aftercooler is employed for reducing the discharge air temperature of the compressor. Such aftercoolers normally use an engine coolant as a recipient heat transfer medium. In the normal single circuit-type cooling system, the coolant is often not below approximately 170.degree. F. at the coolest point in the circuit after the engine has reached its normal operating temperature. Such a temperature is not sufficiently low for an ideal aftercooler operation under certain engine operating conditions. Therefore, if the coolant supplied to the aftercooler could be reduced in temperature, further improvement in engine efficiency would be achieved. Engine cooling systems, such as disclosed in the U.S. Pat. Nos. 4,061,187 to Rajasekaran et al.; 3,872,835 to Deutschmann, disclose coolant circuits allowing one circuit to operate at a higher temperature than does the other. Dual coolant circuit systems solve the problem associated with the need to provide both high and low temperature coolant to different components of an engine.
Previously disclosed designs of cooling systems teach a generally fixed percentage of the recirculatory flow which is split off and passed through a radiator. Then the now cooled coolant from the radiator is passed through an after-cooler which is used to cool the air being blown into the engine. The coolant exiting from the aftercoolers is still at a lower temperature than the recirculatory flow and can be sent back into the main recirculatory flow to cool the engine.
However, none of the references of record describes, illustrates or teaches the novel self-adjusting cooling system for a low temperature air cooling of liquid aftercooled diesel engines as disclosed in the below described subject invention.